The present invention relates to a guide vane segment for a gas turbine, in particular an aircraft gas turbine, comprising at least one radially outer shroud and one radially inner shroud, which extend along a respective circular arc and together form an annular section, wherein, in the radial direction between the outer shroud and the inner shroud, a plurality of guide vanes are arranged adjacently in the peripheral direction and are joined, preferably in a material-bonded manner and, in particular, in one piece, to the inner shroud and to the outer shroud, wherein, in relation to an axial longitudinal direction, the outer shroud comprises an axially front sealing wall element and an axially rear sealing wall element in such a way that the outer shroud and the two sealing walls form a trough-like profile in longitudinal section, wherein, at the axially front or/and rear sealing wall element, at least one relief gap with, for example, a substantially linearly extending main section is provided, which extends substantially radially inward, starting from a radial outer edge of the respective front or/and rear sealing wall element along the sealing wall element.
Directional terms, such as “axial” or “axially,” “radial” or “radially,”, and “peripheral” are fundamentally to be understood as referring to the machine axis of the gas turbine, unless something else ensues explicitly or implicitly from the context.
Relief gaps in guide vane segments of gas turbines serve, in particular, for the purpose of reducing forces in the component due to thermal expansion. It is possible in this way to protect other regions in which cracks would lead to vibrational fatigue of the entire component, in particular of an entire guide vane ring that is formed by a plurality of guide vane segments.
In the case of such relief gaps, the linear main section of which has a radially inner-lying base or gap floor, it has been found that, in the region of the base, high tensile stresses occur during operation of the gas turbine and these can lead to crack formation at the gap in question. The crack formation at such relief gaps results in a reduction in the service life of a guide vane segment or of a guide vane ring that is formed from a plurality of guide vane segments.